Conventionally, various screw-fastening block structures are proposed for connecting a conductive-metal-made bus bar in an electrical junction box to an external terminal with an electric wire via the screw-fastening block.
For example, in PTL 1 (not shown), it is described that a screw-fastening block is made by assembling a stud bolt with a synthetic-resin-made substantially box-shaped bolt cover. The bolt cover has an engaging projection on an outer surface of a vertical sidewall. While the screw-fastening block is inserted upward from a bottom into a set hole (space) of a case main body of a fuse box (electrical junction box), and the stud bolt penetrates a hole of a conductive-metal-made bus bar disposed over the set hole, the engaging projection of the bolt cover is moved over and engaged with a locking projection on an inner wall of the set hole, and the stud bolt is inserted into a hole of a power input terminal with an electric wire over the bus bar, and then the bus bar and the power input terminal are fastened to the stud bolt with a nut so as to be connected to each other.
Further, in PTL 2 (not shown), it is described that a screw-fastening block is composed of a stud bolt and a resin-made block-shaped supporting member. The supporting member has a locking projection and a slider on one sidewall. While the slider is engaged with a slide guide on a sidewall of a box main body of a relay box (electrical junction box) from a bottom, the locking projection is engaged with an arm-shaped elastic locking piece on the sidewall. The stud bolt penetrates a hole of a bus bar upward, and the bus bar is inserted into a hole of the terminal with an electric wire. The bus bar and the terminal are fastened to the stud bolt with a nut so as to be connected to each other. The terminals of the bus bar are connected to a fusible link on the box main body and a terminal of a fuse.
Further, in PTL 3 (not shown), it is described that a screw-fastening block is made by assembling a nut with a resin-made nut holder. The nut holder has a guide projecting wall and an elastic arm-shaped locking piece on one side surface. While the screw-fastening block is inserted upward from a bottom into an insulating block of an electrical junction box, the locking piece is moved over and engaged with a locking projection on an inner wall of the insulating block, and a bolt is inserted into holes of two bus bars and an external terminal with an electric wire on a nut. The external terminal and the both bus bars are fastened with a nut so as to be connected to each other. The terminals of the bus bars are connected to a fusible link on the insulating block and a terminal of a fuse.
FIG. 7 shows an embodiment of a conventional locking structure of a screw-fastening block.
According to this locking structure of a screw-fastening block, a screw-fastening block (bolt block) 63 is composed of a synthetic-resin-made rectangular-shaped screw-fastening block main body 62 and a bolt 61. A pair of locking projections 65 is provided on both sidewalls 64 of the screw-fastening block main body 62. An elastic locking arm 67 is provided downward on an inner wall of a screw-fastening block receiver 66 of an electrically connecting block main body. A conductive-metal-made bus bar 68 is arranged on an upper end of the receiver 66. While the screw-fastening block 63 is inserted into the receiver 66 upward from a bottom, and a thread of the bolt 61 penetrates a hole of the bus bar 68, the locking projection 65 is moved over and engaged with a projection 67a of the locking arm 67.
The locking projections 65 are arranged in vertical grooves 69 provided on sidewalls of the screw-fastening block main body 62. The reason why the screw-fastening block 63 is inserted into the receiver 66 upward from a bottom is because the screw-fastening block 63 cannot be inserted downward from a top by obstruction of the upper bus bar 68. The electrically connecting block main body may be referred as the electrical junction box main body.